Flexible couplings of this kind enable the two pipe ends between which they are interposed to move axially and radially relative to each other so that pipework fitted with such a flexible coupling enables hydraulic coupling to be achieved between two objects that move relative to each other.
The devices used at present for making couplings of this type are generally made either of rubber or elastomer, or else entirely of metal. The first category includes flexible loops that take up space and give rise to head losses, flexible sleeves that take up little space but are generally limited as to pressure, and reinforced flexible membranes which withstand high pressures but are suitable for use with relative movement that is axial only, and which are poorly adapted to pipework of small diameter. The second category includes metal bellows, loops, or various configurations of bends, operating by elastic deformation of the metal, and suffering from drawbacks analogous to those mentioned above for flexible loops and for sleeves, while being less effective in attenuating vibrations transmitted by the pipework.